1. Membrane Dynamics 5

2. The Body Is Mostly Water
Distribution of water volume in the three body fluid compartments
Figure 5-28

3. Osmosis and Osmotic Pressure
Osmolarity describes the number of particles in solution
Figure 5-29

4. Osmosis and Osmotic Pressure
Figure 5-29 (1 of 3)

5. Osmosis and Osmotic Pressure
Figure 5-29 (2 of 3)

6. Osmosis and Osmotic Pressure
Figure 5-29 (3 of 3)

7. Osmolarity: Comparing Solutions
Solution A = 1 OsM Glucose
Solution B = 2 OsM Glucose
B is hyperosmotic to A
A is hyposmotic to B
What would be the osmolarity of a solution which is isosmotic to A? to B?

8. Tonicity
Tonicity describes the volume change of a cell placed in a solution

9. Tonicity
Tonicity depends on the relative concentrations of nonpenetrating solutes
Figure 5-30a

10. Tonicity
Tonicity depends on nonpenetrating solutes only
Figure 5-30b

11. Electricity Review Law of conservation of electrical charges
Opposite charges attract; like charges repel each other
Separating positive charges from negative charges requires energy
Conductor versus insulator

12. Separation of Electrical Charges
Resting membrane potential is the electrical gradient between ECF and ICF
Figure 5-32b

13. Separation of Electrical Charges
Resting membrane potential is the electrical gradient between ECF and ICF
Figure 5-32c

14. Potassium Equilibrium Potential
Figure 5-34a

15. Potassium Equilibrium Potential
Figure 5-34b

16. Potassium Equilibrium Potential
Resting membrane potential is due mostly to potassium
Figure 5-34c

17. Sodium Equilibrium Potential
Can be calculated using the Nernst Equation
Figure 5-35

18. Changes in Membrane Potential
Terminology associated with changes in membrane potential
PLAY
Animation: Nervous I: The Membrane Potential
Figure 5-37

19. Insulin Secretion and Membrane Transport Processes
Low glucose
levels in blood
No insulin
secretion
Metabolism
slows.
ATP
decreases.
Glucose
Cell at resting
membrane potential;
no insulin is released.
KATP
channels open.
Insulin in
secretory vesicles
K+ leaks
out
of cell
Voltage-gated
Ca2+ channel
closed
GLUT
transporter
(a)
Beta cell at rest. The KATP channel is open and the
cell is at its resting membrane potential. K+ 2 3 1 4 5
Figure 5-38a

20. Insulin Secretion and Membrane Transport Processes
Low glucose
levels in blood
Glucose
(a)
Beta cell at rest. The KATP channel is open and the
cell is at its resting membrane potential. 1
Figure 5-38a, step 1

21. Insulin Secretion and Membrane Transport Processes
Low glucose
levels in blood
Metabolism
slows.
Glucose
GLUT
transporter
(a)
Beta cell at rest. The KATP channel is open and the
cell is at its resting membrane potential. 2 1
Figure 5-38a, steps 1–2

22. Insulin Secretion and Membrane Transport Processes
Low glucose
levels in blood
Metabolism
slows.
ATP
decreases.
Glucose
GLUT
transporter
(a)
Beta cell at rest. The KATP channel is open and the
cell is at its resting membrane potential. 2 3 1
Figure 5-38a, steps 1–3

23. Insulin Secretion and Membrane Transport Processes
Low glucose
levels in blood
Metabolism
slows.
ATP
decreases.
Glucose
KATP
channels open.
K+ leaks
out
of cell
GLUT
transporter
(a)
Beta cell at rest. The KATP channel is open and the
cell is at its resting membrane potential. K+ 2 3 1 4
Figure 5-38a, steps 1–4

24. Insulin Secretion and Membrane Transport Processes
Low glucose
levels in blood
No insulin
secretion
Metabolism
slows.
ATP
decreases.
Glucose
Cell at resting
membrane potential;
no insulin is released.
KATP
channels open.
Insulin in
secretory vesicles
K+ leaks
out
of cell
Voltage-gated
Ca2+ channel
closed
GLUT
transporter
(a)
Beta cell at rest. The KATP channel is open and the
cell is at its resting membrane potential. K+ 2 3 1 4 5
Figure 5-38a, steps 1–5

25. Insulin Secretion and Membrane Transport Processes
Glycolysis
and citric
acid cycle
ATP
Ca2+ signal
triggers
exocytosis,
and insulin
is secreted.
Ca2+
(b)
Beta cell secreting insulin. Closure of the KATP channel
depolarizes the cell, triggering exocytosis of insulin.
High glucose
levels in blood
Metabolism
increases.
Glucose
Cell depolarizes and
calcium channels
open.
KATP channels
close.
Ca2+ entry
acts as an
intracellular
signal.
GLUT
transporter 2 3 1 4 5 6 7
Figure 5-38b

26. Insulin Secretion and Membrane Transport Processes
Beta cell secreting insulin. Closure of the KATP channel
depolarizes the cell, triggering exocytosis of insulin.
High glucose
levels in blood
Glucose 1
Figure 5-38b, step 1

27. Insulin Secretion and Membrane Transport Processes
Glycolysis
and citric
acid cycle
(b)
Beta cell secreting insulin. Closure of the KATP channel
depolarizes the cell, triggering exocytosis of insulin.
High glucose
levels in blood
Metabolism
increases.
Glucose
GLUT
transporter 2 1
Figure 5-38b, steps 1–2

28. Insulin Secretion and Membrane Transport Processes
Glycolysis
and citric
acid cycle
ATP
(b)
Beta cell secreting insulin. Closure of the KATP channel
depolarizes the cell, triggering exocytosis of insulin.
High glucose
levels in blood
Metabolism
increases.
Glucose
GLUT
transporter 2 3 1
Figure 5-38b, steps 1–3

29. Insulin Secretion and Membrane Transport Processes
Glycolysis
and citric
acid cycle
ATP
(b)
Beta cell secreting insulin. Closure of the KATP channel
depolarizes the cell, triggering exocytosis of insulin.
High glucose
levels in blood
Metabolism
increases.
Glucose
KATP channels
close.
GLUT
transporter 2 3 1 4
Figure 5-38b, steps 1–4

30. Insulin Secretion and Membrane Transport Processes
Glycolysis
and citric
acid cycle
ATP
(b)
Beta cell secreting insulin. Closure of the KATP channel
depolarizes the cell, triggering exocytosis of insulin.
High glucose
levels in blood
Metabolism
increases.
Glucose
Cell depolarizes and
calcium channels
open.
KATP channels
close.
GLUT
transporter 2 3 1 4 5
Figure 5-38b, steps 1–5

31. Insulin Secretion and Membrane Transport Processes
Glycolysis
and citric
acid cycle
ATP
Ca2+
(b)
Beta cell secreting insulin. Closure of the KATP channel
depolarizes the cell, triggering exocytosis of insulin.
High glucose
levels in blood
Metabolism
increases.
Glucose
Cell depolarizes and
calcium channels
open.
KATP channels
close.
Ca2+ entry
acts as an
intracellular
signal.
GLUT
transporter 2 3 1 4 5 6
Figure 5-38b, steps 1–6

32. Insulin Secretion and Membrane Transport Processes
Glycolysis
and citric
acid cycle
ATP
Ca2+ signal
triggers
exocytosis,
and insulin
is secreted.
Ca2+
(b)
Beta cell secreting insulin. Closure of the KATP channel
depolarizes the cell, triggering exocytosis of insulin.
High glucose
levels in blood
Metabolism
increases.
Glucose
Cell depolarizes and
calcium channels
open.
KATP channels
close.
Ca2+ entry
acts as an
intracellular
signal.
GLUT
transporter 2 3 1 4 5 6 7
Figure 5-38b, steps 1–7

33. Summary Mass balance and homeostasis Law of mass balance Excretion
Metabolism
Clearance
Chemical disequilibrium
Electrical disequilibrium
Osmotic equilibrium

34. Summary Diffusion Protein-mediated transport
Roles of membrane proteins
Channel proteins
Carrier proteins
Active transport

35. Summary Vesicular transport Transepithelial transport Phagocytosis
Endocytosis
Exocytosis
Transepithelial transport

36. Summary Osmosis and tonicity The resting membrane potential
Osmolarity
Nonpenetrating solutes
Tonicity
The resting membrane potential
Insulin secretion